A Field-Based Study of Some Magmatic-Tectonic Effects of Ridge Collision on the Continental Margin of Southern Chile:The Taitao Ophiolite and Near-Trench Instrusions

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The tectonic evolution of orogenic systems developing at convergent margins involves steady state and episodic processes. Steady state processes, such as subduction or arc magmatism have received considerable study, however it is becoming apparent that many orogenic belts have a history involving relatively short, discrete periods of deformation superimposed on the steady state processes. This project examines the effect of a collision of an active spreading center with a convergent margin. The Chile margin triple junction in southern Chile is the best modern example available for study because of its relatively well known, simple kinematic evolution. The work involves study of a 3-4 Ma ophiolite exposed on land 15 km from the trench, silicic plutons near the ophiolite and associated hot springs, and faults and uplifted recent deposits. Results are expected to document a variety of features related to the subduction of an active ridge that may be used in the interpretation of ancient systems.